If you have multiple OST files and want to convert them into PST format, the best way is to use a reliable OST to PST Converter tool like the one from Sysinfo. Unlike manual methods, this utility is designed to handle both single and bulk OST files at once without data loss.

It doesn’t just change OST into PST, but also supports other formats like MBOX, PDF, EML, and more. On top of that, it lets you migrate your OST data (emails, contacts, calendars, tasks, etc.) directly into cloud platforms such as Office 365, Gmail, Yahoo Mail, Thunderbird, and others.